The invention relates to an LED assembly, a LED fixture, a method for controlling an LED assembly, and to a software program comprising program instructions to, when loaded into a processing device of an LED assembly control circuit, perform such method.
In the past years, application of LEDs for lighting purposes are seen more and more frequently. In such applications, use may be made of LEDs having a same colour, however frequently use is made of groups of LEDs each having a different characteristic, e.g. a different colour. It is for example possible that use is made of red, green and blue LEDs, a synchronous or pulsed operation of the differently coloured LEDs may thereby provide a desired colour, such as white, a whitish colour, or any other desired colour which can be made by e.g. combining two or more of the LEDs. In order to operate the LEDs, a variety of driving circuits and control circuits has been proposed. Thereby, a characteristic of the group of LEDs may be measured, such as a light output, a forward voltage, an LED forward current, etc. As however a plurality of groups of LEDs may be applied, such sensing would be required to be provided for each of the groups, which necessarily increases hardware costs and complexity. As an example, in case that light output is measured, separate light sensors would be required for each of the groups (e.g. by applying an optic coupler which directs a percentage of the light generated by each of the groups to a respective light sensor). Similarly, sensing any other parameter (such as LED forward voltage, LED temperature, LED forward current, etc), sensing circuits are applied for each of the groups.